Electrical picture-transmission system



Dec. 28 1926. 1,612,005

J. D. ELLSWORTH ELECTRICAL PICTURE TRANSMISSION SYSTEM Filed April 1 8l1925 n 14 ,Il

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l. i. l a l n u l n I l \.k n I l n u n l i a. 7 /f/y. 5 .Q 19'/ (/'I Q/n Y mvENmR jf QY/SawJf/f ATTQRNEY Patented Dec. 28, 1926.

UNITED STATES PATENT OFFICE.

JAMES D. ELLSWORTH, OF BRONXVILLE. NEXV YORK, ASSIGNOR TO AMERICAN TELE-PHONE AND TELEGRAPH COMPANY, A CORPORATION OF NEW YORK.

ELECTRICAL PICTURE-TRANSMISSION SYSTEM.

Application led April 18, 1925.

An object of my invention is to provide a new and improved system ofrecording received pictures in the electrical transmission of pictures.Another object of my invention is to provide for recording the receivedpicture in a half tone dot7 pattern. Still another obj ect of myinvention involves recording the picture primarily in parallellines ofwidth varying according to the light shade, and deriving therefrom apicture recorded in dot pattern. These objects of my invention andvarious others will become apparent on consideration of a limited numberof specific embodiments of the invention which l have chosen toillustrate and describe in the following specification taken with theaccompanying drawings. It will be understood that the followingdescription relatesto these examples 'of the invention and that theinvent-ion will he defined in the appended claims.

Referring to the drawings, .Figure l is adiagram illustrating picturereceiving apparatus. Fig. 2 is a diagram illustrating how the varyingshades may be indicated in a received picture record, and Figs. 3 to 9are further diagrams showing how records of the character shown Vin Fig.2 may be combined to get a dot pattern in the final record.

Light from the source il passes through the light valve lll and isfocused by the lens 13 on the sensitive film 16. This film 16 is wrappedon a drum 17 that is rotated on its axis and at the same time traversedlongitudinally hy the engagement of the screwthreaded shaft 18 with asuitable support. Thus it will be seen that the spot of the film 16 thatreceives the light through the lens 13 describes a helical course. Thedegr'ee of light on this spot is determined by the light valve 14, whichis controlled by the incoming picture transmitting current.

The record on the film 16 will accordingly he a helical line of varyingwidth as determined hy the width of opening oi3 the light valve 14. thevariation of shade by the variation of the. width of the lines isindicated.

Although the halt tone edect will be clearly obtained by the picturerecorded as shown in Fig. 2, it may be desirable in some instances tohave this eii'ect secured by a dot pattern. For this purpose I transmitthe picture twice9 the second time with the lines This is shown in Fig.2 where4 Serial No. 24,202.

of Fig. 2 running in a direction at a right angle to their direction inthe first instance. The two received pictures are represented by thesimple diagrams of Figs. 3 and 3., which represent two picture positivesas received from the line. It will be seen that the shade is relativelylight at the left and darker at the right in each of these positives.

These two positives in the form of films are then superposed and thecommon ne a.- tive is made from them, which it will rea ily lie seen hasthe appearance shown in Fig. 4. This negative is then printed on a metalplate, and the prints from this plate have the character shown in Fig. 5where the light shade is given by large white squares and the dark shadeis given by smaller white squares. The positive picture as recorded inFig. 5 may be more pleasing and satisfactory than either of thepositives of Fig. 3 or Fig. 3a.

Another mode of procedure is to get the two positives of Fig. 3 and Fig.3a and print separate negatives from them as shown in Fig. 6 and Fig.6a. These negatives are then superposed and a common positive printedfrom them as shown in Fig. 7. This positive is then employed to get acorresponding negative as shown in Fig. 8, and this negative is printedon a metal plate and from the plate prints are taken as shown in Fig. 9,where the fine black dots appear in the high lights and the large blacksquares in the'shadows. v

Figs. 5 and 9 may he contrasted and it will be seen that the two methodsgive somewhat different results. Fig. .5 has somewhat dull high lightsbut very deep shadows,

vwhereas Fig, 9 has very bright high lights andthe shadows are not verydeep. The entire picture, according to the method of Fig. 9, willbegconsiderably lighter than according to Fig. 5. One advantage of themethod of Fig. 5 is that a less number of photographic operations arerequired, and thus a cleaner printing negative is involved.

I claim:

i.. The method of reproducing a picture, which consists in electricallytransmitting and recording it with its original shades yin 'parallellines of width determined by the shades electrically transmitting andrecording the picture again with the lines in an angular direction withrespect to the lines of the first record, and superposing the records. Av

2. The method of reproducing a picture, which consists in electricallytransmitting and recording it with its original shades in parallel linesof width lcorresponding to the tone values of the various parts of thepicture, electrically transmitting and making another similar record,with the lines extending at an angle relatively to the lines of thefirst record, and superposing the two records and printing therefrom toget a dot pattern With the shade corresponding to the magnitude of thedots.

In testimony whereof, I have signed my name to this specification this17th clay of April 1925.

JAMES D. ELLSWORTH.

